[Boost-bugs] [Boost C++ Libraries] #8310: Wrong results with overlapping polygons

Subject: [Boost-bugs] [Boost C++ Libraries] #8310: Wrong results with overlapping polygons
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-03-19 15:04:56

#8310: Wrong results with overlapping polygons
--------------------------------------------------+-------------------------
 Reporter:  Paolo Giangrandi <paolo@…>            |       Owner:  barendgehrels
     Type:  Bugs                                  |      Status:  new          
Milestone:  To Be Determined                      |   Component:  geometry     
  Version:  Boost 1.52.0                          |    Severity:  Problem      
 Keywords:                                        |  
--------------------------------------------------+-------------------------
 Many algorithms from `boost::geometry` (`difference`, `intersection`,
 `union_`, `disjoint`, `sym_difference`, `intersects`, possibly more) give
 wrong results with some pairs of polygons.

 I could find many pairs of polygons (could only find pairs of polygons
 sharing part of an edge since I'm working with this kind of polygons) that
 are wrongly treated as if they weren't intersecting by all the
 aforementioned algorithms.

 Here some examples:
 {{{
 POLYGON(( -2.559375047683716 -0.615625500679016, -2.559375047683716
 0.384374797344208, 7.940625190734863 0.384374588727951, 7.940625190734863
 -0.615625441074371 ))
 POLYGON(( 1.000000000000000 0.384374707937241, 1.000000000000000
 0.000000000000000, 0.000000000000000 0.000000000000000, 0.000000000000000
 0.384374737739563 ))
 }}}

 {{{
 POLYGON(( 0.000000000000000 0.373437941074371, 1.000000000000000
 0.373437792062759, 1.000000000000000 0.000000000000000, 0.000000000000000
 0.000000000000000 ))
 POLYGON(( -2.592187881469727 -0.626561701297760, -2.592187643051147
 0.373438000679016, 7.907812595367432 0.373437851667404, 7.907812595367432
 -0.626561224460602 ))
 }}}

 {{{
 POLYGON(( 1.000000000000000 2.531045913696289, 1.000000000000000
 3.000000000000000, 2.000000000000000 3.000000000000000, 2.000000000000000
 2.531045913696289 ))
 POLYGON(( 5.204249382019043 3.531043529510498, 5.204247951507568
 2.531045675277710, -5.295750617980957 2.531046152114868,
 -5.295751094818115 3.531045913696289 ))
 }}}

 I'm working on Linux x86-64 (ArchLinux), and could reproduce this bug both
 with G++ 4.7.2 and clang 3.2.

 I'm using the following types to store points and polygons:
 {{{
 typedef boost::geometry::model::d2::point_xy<float> point;
 typedef boost::geometry::model::polygon<point, true, false> polygon;
 }}}

 The attached source file (C++11) can be used to reproduce this bug.

 I believe this bug could be related to
 https://svn.boost.org/trac/boost/ticket/8183 .

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/8310>
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